The present invention relates to a mechanism used for locking a valve that provides positive control of the valve lock. Preferably, the invention can be used to provide a positive locking mechanism to prevent the valve from changing position unintentionally.
There exists a need for a valve locking mechanism that provides positive control of the valve lock. Such devices are particularly suited for use with water valves located on vehicles such as firetrucks in order to prevent the valve from changing position unintentionally while it is either in use or awaiting use. Preferably, such an invention can be used with an adjustment rod (xe2x80x9cpush-pull rodxe2x80x9d) to provide a positive locking mechanism which can be activated by the user to prevent the valve from changing position and then deactivated when it is desired to alter the valve position.
Current competing designs suffer from the problem that the push-pull rod is capable of xe2x80x9cslippingxe2x80x9d thereby permitting an alteration of the valve position. The present invention solves this problem by use of a valve locking mechanism that provides a positive barrier to push-pull rod movement which requires rotation of the push-pull rod by a certain predefined amount to defeat the barrier and thereby permit valve movement.
Accordingly, it is an object of the present invention to provide a positive valve locking mechanism to prevent the valve from changing position unintentionally.
It is another object of the present invention to provide a mechanism which is suited for use with water valves located on vehicles such as firetrucks in order to prevent the valve from changing position unintentionally while it is either in use or awaiting use.
It is another object of the present invention to provide a mechanism which can be used with an adjustment rod (xe2x80x9cpush-pull rodxe2x80x9d) to provide a positive locking mechanism which can be activated by the user to prevent the valve from changing position and then deactivated when it is desired to alter the valve position.
It is another object of the present invention to provide a valve locking mechanism that provides a positive barrier to push-pull rod movement which requires rotation of the push-pull rod by a certain predefined amount to defeat the barrier and thereby permit valve movement.
The positive locking valve control device of the present invention preferably comprises a push-pull rod having a toothed configuration that is engaged at different positions by a spring mechanism on the valve locking device in order to hold the push-pull rod and thereby the valve securely in place. To adjust the opening of the valve, the push-pull rod can be rotated by some predefined amount (such as 90 degrees) clockwise or counter-clockwise. This rotation frees the locking spring on the valve locking device from the teeth aligning it with a side of the push-pull rod thereby permitting linear movement of the rod to cause a corresponding adjustment in valve position. The rod is then xe2x80x9cpushed inxe2x80x9d or xe2x80x9cpulled outxe2x80x9d to adjust the size of the valve opening until the desired flow through the valve is obtained. Once the desired flow is achieved the push-pull rod is then rotated back through the predefined angle to its original position where the spring engages the teeth in the push-pull rod to prevent any further linear motion of the push-pull rod thereby effecting a lock of the valve at the selected position.
An improvement to the invention is the addition of a rotational limiter to the push-pull rod. The rotational limiter limits the rotation of the push-pull rod to a predefined amount (such as 90 degrees) from its normal locked position. This simplifies the operation of the invention by stopping the rotation at the optimal angle for linear adjustment. This is the angle where the spring provides no resistance to linear motion. This can preferably be accomplished by placing a pin in the main housing for the push-pull rod and using a limiter attached to the push-pull rod that comes into physical contact with the pin at the desired angle to provide a barrier to rod movement that prevents further rotation. The geometry of the limiter can take advantage of the preferred xe2x80x9cdouble dxe2x80x9d shape of the rod to prevent undesired rotation.
Another improvement to the invention is the addition of a spring loaded ball plunger to provide tactile feedback when the push-pull rod is returned to its normal locked position. This can be accomplished by placing a hole in the rotational limiter that lines up with the ball plunger when the rod is rotated to the locked position.
Another improvement to the invention is the addition of tactile feedback when the maximum rotation to the predefined valve angle (such as plus or minus 90 degrees) is reached. This again can be accomplished through use of the ball plunger by designing the geometry of the rotational limiter such that when the maximum rotation is reached the ball plunger extends itself in the opposite direction from its position when the valve is locked.
Another improvement to the invention is the addition of bushings to facilitate easier linear movement of the push-pull rod. This can be accomplished by providing bushings that fit between the push-pull rod and its main housing to provide a surface with less friction than would otherwise be experienced with metal-to-metal contact.
These and other advantages of the invention will become apparent from a perusal of the following detailed description of the presently preferred embodiments of the invention taken in connection with the accompanying drawings.